The present invention relates to a method for traffic load control in a telecommunication network consisting of at least one radio terminal and at least one radio transceiver device, each radio transceiver device defining a cell of the network being controlled by a network control device.
Recently, telecommunication networks have widely spread and an increasing number of subscribers uses the benefits of telecommunication, in particular radio telecommunication networks.
Such networks consist of a plurality of radio transceiver devices or base stations BS, respectively, which effect transmission between the base stations BS and radio terminals (mobile stations) MS of the individual subscribers. The plurality of base stations BS is controlled by a network control element such as for example a radio network controller RNC.
Within a telecommunication network, not only speech is transmitted, but also other data can be exchanged, such as for example facsimiles, data transmitted by short message services SMS, data polled from the internet and so on. Those data are often referred to as packet data, since they are transmitted in respective data packets or files, respectively.
Thus, the more subscribers are registered to such a network and the more data, speech data and/or packet data, can be transmitted using radio telecommunication networks, the higher will be the traffic load imposed on such systems.
However, the maximum traffic capacity that can be handled by radio telecommunication network is limited by the available radio resources RR such as available frequencies, and/or channelization codes, etc.
If the traffic load is continuously increasing, a point might be reached at which the system is overloaded. Then, for example, no new communication may be established.
Additionally, data transmission via already established communication links will be adversely effected due to interference phenomena, which causes a drawback for respective users in that they can not communicate in good quality. It is even possible that as a worst case scenario an overloaded network may xe2x80x9ccollapsexe2x80x9d and all ongoing communication links will break off.
Hence, it is an object of the present invention to provide a method for traffic load control in a telecommunication network consisting of at least one radio terminal and at least one radio transceiver device, each radio transceiver device defining a cell of the network being controlled by a network control device, by means of which the above mentioned drawbacks can safely be prevented.
Accordingly, in order to achieve the above object, the present invention provides a method for traffic load control in a telecommunication network consisting of at least one radio terminal and at least one radio transceiver device, each radio transceiver device defining a cell of said network being controlled by a network control device; comprising the steps of setting a first reference load value for the load of a respective cell; monitoring the load of said respective cell, and in response to the load exceeding the first reference load value, manipulating the power control to decrease the transmission power levels in the cell.
Thus, due to the load reference value being defined, a first (fast) load control method can be activated when the first reference load value is exceeded. According to advantageous refinements, a second (slower) load control method can additionally be activated when i) the first reference load value is exceeded (simultaneous activation), ii) when a subsequent monitoring yields that the first (fast) load control did not reduce the traffic load below said reference value, or iii) when even with the first (fast) load control being activated the traffic load also exceeds a second reference load value. The second reference load value can be equal to or higher than the first reference load value.
In particular, the present invention describes a method of a fast (first) load control method, in that during an overload situation (load above a certain reference load value) the load is controlled or reduced, respectively, temporarily and per base station BS by affecting or manipulating power control commands (neglecting TPC commands in downlink, overwriting TPC commands in uplink).
In addition, as already mentioned, the above fast (xe2x80x9cimmediatexe2x80x9d) load reduction is supplemented by a xe2x80x9cslowxe2x80x9d (second) load control method in that the transmission bit rates are affected to correct the overload situation in a more permanent manner, if the first load control method turned out to be not sufficient, or in that connections are being removed from the cell.
Favorable refinements of the present invention are as defined in the dependent claims.
Thus, the present invention provides a novel method for load control which is easy to implement in existing products an which prevents the above described drawbacks.
In particular, the present invention presents a simple load control method to be implemented into existing systems and/or devices, while different measures that can be initiated are harmonized with each other to present one simple method for traffic load control. The present invention provides a fast load control, i.e. first stage load control, respectively, and handled by a respective base station BS in a sector defined by the base station, which aims to temporary reduction of traffic load by denying download DL transmit power TPC commands and overwriting uplink UL transmit power TPC commands (or by reducing a target value for the energy per bit to noise power density ratio (Eb/N0) in the base station during overload) if overload is encountered. If this is still not sufficient to reduce the network traffic load, a second stage load control handled by a radio network controlling device of the network RNC will trigger other actions in order to reduce system load more permanently, for example by reducing bit rates. Thus, decentralized and centralized load control actions are advantageously combined in the proposed method.
Moreover, the proposed load control method can keep the system, i.e. the telecommunication network stable and throttle back the overall load in a controlled fashion.
Additionally, due to the fast first stage load control method, a load margin as the difference between an acceptable (target) load level and a maximum tolerable load level (threshold) can be reduced which increases the network system capacity and thus represents an advantage for the network operator. Target and threshold level could even be set to be identical.
The present invention will be more readily understood when read in conjunction with the description of the accompanying figures.